<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        var Chinese = prompt("请输入语文成绩");
        var math = prompt("请输入数学成绩");
        var english = prompt("请输入英语成绩");
        var chemistry = prompt("请输入化学成绩");
        var hisrory = prompt("请输入历史成绩");
        var average = (+Chinese + +math + +english + +chemistry + +bhisrory) / 5;
        document.write(average)
        var level = Math.floor(average / 10);
        switch (level) {
            case 10:
                alert("优秀");
                break;
            case 9:
                alert("优秀");
                break;
            case 8:
                alert("良好");
                break;
            case 7:
                alert("一般");
                break;
            case 6:
                alert("较差");
                break;
            default:
                alert("很差");
                break;

        }
    </script>
</body>

</html>